1. Field of the Invention
The present invention relates to an ozone generating apparatus, and more particularly to an apparatus for generating ozone by mixing oxygen gas and nitrogen gas in a predetermined ratio.
2. Description of the Related Art
FIG. 1 is a partially cutaway schematic view illustrating a portion of a conventional ozone generating apparatus. In this figure, oxygen gas is supplied to a cylindrical discharge tube 1 from an oxygen gas supplying tube 2. In the center of the discharge tube 1 is disposed an electrode 3 for exciting oxygen introduced into the discharge tube 1 and supplying the energy to generate the ozone. The discharge tube 1 to which the oxygen gas supplying tube 2 is connected communicates with a discharge tube 4 adjacent to the oxygen gas supplying tube 2. An ozone discharge tube 5 for discharging generated ozone is connected to the discharge tube 4. Since the discharge tubes 1 and 4 reach high temperatures, their surroundings are cooled by cooling water from a cooling water storage container 6. This container 6 is grounded, and a cooling water input tube 7 and a cooling water discharge tube 8 for inputting and discharging cooling water respectively are provided on the bottom of the container 6.
A conventional ozone generating apparatus is constructed as mentioned above, and silent discharge is performed in the discharge tubes 1 and 4 into which oxygen gas is input. The oxygen gas is excited by this silent discharge and ozone is generated from the excited oxygen. The ozone generated is discharged from the ozone discharge tube 5 together with oxygen gas which has not reacted.
In the ozone generating apparatus mentioned above, where highly pure oxygen gas (purity: 99.95% or more) for use in the manufacture of semiconductors is used as a source gas, the efficiency of the generation of ozone may sometimes fall considerably below that where ordinary bottled oxygen gas (purity: up to 99.95%) is used. Also, where the above-mentioned bottled oxygen gas is used as a source gas, there has been a problem in that the efficiency of the generation of ozone differs depending on the purity of the bottled oxygen gas and stable generation of ozone is thereby rendered impossible.